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Academic Commons Search Resultsen-usResponse to Comment on "Ascent of Dinosaurs Linked to an Iridium Anomaly at the Triassic-Jurassic Boundary"http://academiccommons.columbia.edu/catalog/ac:142422
Olsen, Paul E.; Sues, Hans-Dieter; Rainforth, Emma C.; Kent, Dennis V.; Koeberl, Christian; Huber, Heinz; Montanari, Alessandro; Fowell, Sarah J.; Szajna, Michael J.; Hartline, Brian W.http://hdl.handle.net/10022/AC:P:11966Tue, 13 Dec 2011 00:00:00 +0000Our recent study on the nature of the ascent of the dinosaurs (1) argued three main points: (i) that a major terrestrial tetrapod mass extinction is concentrated at the palynologically identified Triassic-Jurassic boundary in eastern North America (based on footprints and bones); (ii) that truly large predatory dinosaurs appear immediately after the boundary (based on footprints); and (iii) that both the boundary and the mass extinction level are associated with a modest Ir anomaly and fern spike, plausibly of asteroid or comet impact origin. Although the comment of Thulborn (2) addresses a number of paleontological issues in (1), his only point salient to the conclusions of our paper is his extraordinary claim that very large theropod dinosaurs were already present in the Carnian, some 20 million years or so before the Triassic-Jurassic boundary [in contrast to our assertion in point (ii), above].Paleontologypeo1, ecr18, dvk2Lamont-Doherty Earth Observatory, Earth and Environmental SciencesArticlesAscent of Dinosaurs Linked to an Iridium Anomaly at the Triassic-Jurassic Boundaryhttp://academiccommons.columbia.edu/catalog/ac:142418
Olsen, Paul E.; Kent, Dennis V.; Montanari, Alessandro; Rainforth, Emma C.; Huber, Heinz; Fowell, Sarah J.; Sues, Hans-Dieter; Koeberl, Christian; Szajna, Michael J.; Hartline, Brian W.http://hdl.handle.net/10022/AC:P:11963Mon, 12 Dec 2011 00:00:00 +0000Analysis of tetrapod footprints and skeletal material from more than 70 localities in eastern North America shows that large theropod dinosaurs appeared less than 10,000 years after the Triassic-Jurassic boundary and less than 30,000 years after the last Triassic taxa, synchronous with a terrestrial mass extinction. This extraordinary turnover is associated with an iridium anomaly (up to 285 parts per trillion, with an average maximum of 141 parts per trillion) and a fern spore spike, suggesting that a bolide impact was the cause. Eastern North American dinosaurian diversity reached a stable maximum less than 100,000 years after the boundary, marking the establishment of dinosaur-dominated communities that prevailed for the next 135 million years.Paleontologypeo1, dvk2, ecr18Lamont-Doherty Earth Observatory, Earth and Environmental SciencesArticles